The present invention relates to a drive coupling for coupling together, and providing drive between, two rotatable members.
The invention is concerned, in particular, with a drive coupling of the type comprising a coupling member, for example a socket member, which is shaped to receive a splined shaft. The coupling member has internal spline-engaging elements so that, when the shaft is fully inserted into the coupling member, a rotational driving engagement is formed between the shaft and the coupling member. The coupling member and the splined shaft are each connected to, or form part of, a respective one of the rotatable members that are to be coupled together.
Drive couplings of that type are known, for example for coupling together two rotatable shafts. They are used, for example, in some xerographic copying machines, where they facilitate assembly during manufacture, and also dismantling and reassembly during servicing (although they have many other applications also). Problems can arise, however, if the shafts or other rotatable members are angularly misaligned when they are being coupled together because it may then be difficult or, in some cases, impossible, to make the required connection between them. It is known to chamfer or taper the ends of the splines of the splined shaft, to facilitate insertion of the shaft into the coupling member but, despite this, difficulties may still occur.
In the field of xerography, drive couplings of the type referred to above have been used in copying machines that employ replaceable cassettes to house some or most of the components required for the xerographic process. More particularly, it is known to use such a coupling to couple components within a cassette to a rotational drive member in the main body of the machine. In a known arrangement, such as disclosed in UK patent application GB-A-2 214 609, the splined shaft extends from the cassette and the intention is that it should engage in the coupling member as the cassette is being inserted into the machine. If the shaft is not correctly oriented, however, there can be difficulties in making the coupling and damage may result. With a view to overcoming this problem, a coupling has been proposed in which a limited amount of rotational movement is permitted between either the splined shaft or the coupling member and its respective rotatable member.
U.S. Pat. No. 4,437,782 to Geisthoff discloses a splined hub assembly for connecting two shafts which facilitates angular alignment of the splines relative to one another. The assembly has an opening formed in the wall of one of the members in which a ball is loosely held. The axial distance between the identical or greater than the axial length of the cylindrical ball contacting surface. Such a configuration allows for rotation of one of the splined members to facilitate alignment.
U.S. Pat. No. 4,859,110 to Dommel discloses an automatic coupling device for connecting a splined shaft to a corresponding internally splined yoke. A collar with flexible tabs is manually rotatable to an unlocked position and triggered to rotate to a locked position by locking balls. A torsional spring in the collar produces the rotation of the coupling device.
U.S. Pat. No. 2,910,842 to Sensinig discloses a coupling for use with a splined shaft with a yoke, whereby one member may be brought into alignment with the other. The splines are cut with angular faces. Upon insertion of the splined shaft into the yoke, a guide member rotates either or both members to bring them into alignment.
UK Patents GB-A-1 046 028; GB-A-1 463 813; GB-A-1 570 330; GB-A-509 508; and European Patent EP-A-0 233 813 disclose various other spline couplings for used in torque transmitting devices, automobile steering mechanisms, and the like.